Win big prizes and improve leadership

Convert your influence points into leadership skill and enormous amounts of money. To do this, follow the steps:

1. Be a member of a kingdom and pile up some influence (300+ should do it, the more the better). You can gain influence by doing quests, participating in wars and passively from kingdom policies.
   
2. At a peaceful time, create an army and invite as many nobles as you can. With a big enough army and a few focus points in leadership, you will be receiving multiple leadership skill points per day just by running around and partying hard.
   
3. Run around different cities, searching for tournaments. While in a city, you can go to the arena master and ask him where there are tournaments nearby.
   
4. Win these tournaments. You will discover that prizes for these tournaments will often be among the best items in the game, with pricetags in tens of thousands of gold.

Basic principle is that tournament prizes depend on the number of nobles that attend a tournament. When you will come to a city with an army, most of the nobles will gladly participate in the tournament. In the meantime, by running around with a huge army your leadership improves passively.